A handover technology for allowing a terminal to continuously receive a service provided from a base station during moving for ensuring mobility of the terminal in a wireless communication system has been proposed. The handover refers to a technology that as a terminal moves from a serving base station (BS) in which the terminal is receiving a service to another base station (Target BS), data contexts which are currently transmitted/received to/from the serving BS are transferred to the target BS with a minimum interruption time for continuous communication. The handover technology may ensure the service continuity for the mobile terminal.
Especially, among various types of handovers, an Entry Before Break (EBB) handover of disconnecting a link to the serving BS after entry into the target BS in a state of maintaining the link connected to the serving BS has an advantage of enabling a continuous data reception from the serving BS even during handover.
However, during the EBB handover, if a re-entry process to the target BS has been delayed or the handover has failed due to an error occurred in the handover procedure, there is no way to inform the current state to the serving BS. Consequently, a continuous service from the serving BS cannot be guaranteed or a handover delay may be caused.